1. Field of the Invention
The present invention relates to identifying signals accessible to subscribers in hybrid fiber coaxial (HFC) interactive networks.
2. Background Art
A hybrid fiber coaxial (HFC) network is a telecommunications network in which optical fiber and coaxial cable are used in different portions of the network. The fiber and cable along with other HFC equipment make up the “plant” of the HFC network. An HFC network connects a head end (HE) to subscribers for the HE to communicate broadband content (such as video, data, and voice) to the subscribers. The fiber portion of the plant is generally connected to the HE whereas the cable portion of the plant is generally connected to the subscribers. An interactive HFC network provides two-way communications between the HE and the subscribers such that the subscribers are enabled to transmit information to the HE.
A subscriber has customer premises equipment (CPE) such as a set-top-box (STB) which connects the subscriber to the HFC interactive network. The CPE receives broadband signals transmitted by the HE. Typically, a single HE serves a plurality of subscribers and subsets of the subscribers are arranged in different subscriber service groups. In general, the HE provides a multitude of broadband signals for the subscribers. Typically, however, all of the signals are not available or accessible by all of the subscribers. For instance, a set of some of the signals are accessible to the subscribers in one service group whereas a different set of some of the signals are accessible to the subscribers in a different service group.
That is, in an HFC interactive network, the CPE of a subscriber can connect to a multitude of signals that have varying degrees of uniqueness within the network. As such, certain ones of the signals are available or accessible to select service groups. Some signals may appear in only one service group whereas other signals may appear in many different or all of the service groups.
Enabling the HE to determine the set of signals a particular subscriber can access is difficult for many reasons. One reason is that the plant of the HFC interactive network is continuously changing. Another reason is that the CPE often has no mechanism to determine the difference between the signals. If the CPE of a subscriber does have such capabilities, then often these capabilities are limited to discovering only a few of the multitude of signals. Lastly, communications bandwidth is a scarce resource and requiring the CPE to send information regarding all signals accessible to the HE is too burdensome.
To date, most discovery mechanisms either require a full discovery of all signals or require a limited discovery of one piece of information found in either data within a single signal or data related to upstream communication paths. The latter method also requires that an operator manually create a table mapping each signal to the grouping of subscribers served by those signals. The discovered data is an index to the table.
A challenge with the full discovery method is that limited communications bandwidth limits the scalability of this method. In other words, as the number of signals used for interactivity grows, the ability to send all of the information to the HE diminishes. Also, the time in which it takes to discover the information increases. Usually there is no time at which the CPE is not in use. Therefore, the amount of time spent searching for signals is often limited. In any event, systems that rely solely on full discovery are typically provide only a limited set of the available signals to the HE.
A challenge with the limited discovery method is that the manual mapping requires much time and effort to maintain. Often the plant of an HFC interactive network changes and the changes may not be reflected in the mapping, thus causing denial of service to the subscribers. Also, mis-configurations sometimes occur which require much effort to fix. These mis-configurations are typically only uncovered after a subscriber has lost service.